Photopyroelectric study of specific heat, thermal conductivity, and thermal diffusivity ofCr2O3at the Néel transition

A photopyroelectric technique has been used to simultaneously measure the critical behavior of specific heat, thermal conductivity, and thermal diffusivity of ${\mathrm{Cr}}_2$ ${\mathrm{O}}_3$ at the antiferromagnetic-paramagnetic phase transition. An Ising-like behavior has been found for ‖${\mathit{t}}_{\max }$‖≤3×${10}^{\mathrm{-}3}$ with α=0.10±0.02 and A/A’=0.48±0.03. A possible crossover between Ising and Heisenberg behaviors has been found if ‖${\mathit{t}}_{\max }$‖ is increased. Thermal diffusivity data have been fitted according to the model for a uniaxial antiferromagnet with energy conservation for ‖${\mathit{t}}_{\max }$‖≤3×${10}^{\mathrm{-}3}$ with a critical exponent b=-0.11±0.02. A correction term similar to the static correction to scaling factor has been introduced in the fitting function. No anomaly has been found in thermal conductivity.